Air filter and air filter system

Abstract

An air filter and frame that cooperate to require alignment of the filter in a desired orientation in order for insertion to occur. At least one edge of the filter is offset from a right angle relative to other edges and the faces of the filter, and an obstruction is formed in the frame so that the filter can be inserted into the frame in only the desired orientation. Preferably two opposing edges of the frame are angled, and obstructions, such as small rails, are mounted in opposing sidewalls of the frame.

The invention claimed is: 
     
       1. A gas filtration apparatus comprising:
 (a) a substantially planar gas filter having a filter frame with substantially parallel front and rear faces and first and second peripheral edges on a perimeter of the filter, and filtration media within the filter frame, wherein at least the first filter frame edge is substantially planar and is aligned relative to the front face at an angle substantially greater than 90 degrees, and aligned relative to the rear face at an angle substantially less than 90 degrees; 
 (b) a gas filter receptacle frame having at least one sidewall defining a substantially planar void into which the filter is inserted in a direction substantially parallel to a plane of the filter, when the filter is inserted in a desired orientation, for maintaining the gas filter in a path of gas flow; and 
 (c) an obstruction formed on said at least one receptacle frame sidewall for accommodating the first edge of the filter frame during insertion of the filter into the void in the desired orientation of the filter, and for interfering with the second edge of the filter frame during insertion of the filter into the void in an undesired orientation of the filter. 
 
     
     
       2. The gas filtration apparatus in accordance with  claim 1 , further comprising a second receptacle frame sidewall, a third of the filter frame's edges is aligned relative to the filter's front face at an angle substantially greater than 90 degrees and aligned relative to the filter's rear face at an angle substantially less than 90 degrees and an obstruction is formed on the second receptacle frame sidewall for accommodating the third edge of the filter during insertion of the filter into the void in the desired orientation of the filter, and for interfering with a fourth edge of the filter during insertion of the filter into the void in an undesired orientation of the filter. 
     
     
       3. A gas filtration apparatus comprising:
 (a) a substantially planar gas filter having a substantially gas-impermeable filter frame containing a substantially gas-permeable filtration media, the filter frame having substantially parallel front and rear faces and peripheral edges on a perimeter of the filter, wherein at least a first of the filter frame's gas impermeable edges is substantially planar and is aligned relative to the front face at an angle substantially greater than 90 degrees, and aligned relative to the rear face at an angle substantially less than 90 degrees; 
 (b) a gas filter receptacle frame having at least one sidewall and a substantially planar void into which the filter is inserted, during filtration of a gas through the filter's substantially gas-permeable filtration media when the filter is inserted in a direction substantially parallel to a plane of the filter in a desired orientation, for maintaining the gas filter in a path of gas flow; and 
 (c) an obstruction formed on said at least one receptacle frame sidewall for accommodating the first substantially gas-impermeable edge of the filter frame when the filter is inserted into the void in the desired orientation of the gas filter receptacle frame, and for interfering with a second edge of the filter frame when the filter is aligned with the void in an undesired orientation. 
 
     
     
       4. A gas filter for use in a gas filter receptacle frame having at least one sidewall defining a substantially planar void into which the filter is configured for insertion in a desired orientation for maintaining the gas filter in a path of gas flow, the filter comprising:
 (a) a substantially planar gas filter having a filter frame with substantially parallel front and rear faces and peripheral edges on a perimeter of the filter, and filtration media within the filter frame, wherein at least a first filter frame edge is substantially planar and is aligned relative to the front face at an angle substantially greater than 90 degrees, and aligned relative to the rear face at an angle substantially less than 90 degrees to form a cavity that, when the filter frame is inserted into the void in a direction substantially parallel to a plane of the filter in the desired orientation of the filter, receives an obstruction formed on said at least one receptacle frame sidewall, and wherein a second edge of the filter frame is configured to interfere with the obstruction during attempted insertion of the filter into the void in an undesired orientation of the filter.